Are 3D-printed carbon fibre re-enforced propeller blades suitable for use in high performance boats?

High-performance motorboats find a range of applications from military uses to leisure vessels, many of these boats are powered by engines with propellers. At present most of the propellers used in high-performance boats are manufactured from stainless steel. This project explores the possibility of manufacturing high performance boat propellers from a 3D printable carbon fibre re-enforced plastic material. This anisotropic, strong and lightweight material is seemingly ideal for the application of high-performance boat propellers and has found applications in other marine propeller manufacture. This project seeks to answer the engineering question posed above using theoretical methods to provide an insight into the potential application of composites in high-performance boat propeller manufacture. The project does not seek to fully develop an argument for the use of such materials and as such considers only the mechanical and fluid dynamics aspects of the problem and does not explore the commercial feasibility of a composite solution. To assess the feasibility of using composite materials a series of quasi-static mechanical and computational fluid dynamic calculations are performed. A model propeller is taken and developed into a quasi-static model to assess the strength of the composite and the suitability of the composite as a material for use in propellers. The results from the composite material are compared with a traditional propeller material. Both the composite and traditional propeller are then imported into a computational fluid dynamics solver, and the hydrodynamic properties are calculated using a moving reference frame. The properties are determined across a range of water flow rates and propeller rotational speeds using a Python computer program and ANSYS Fluent. The static and dynamic results are then analysed and compared. The static results show that a composite propeller is likely to undergo significant deformation when pressure is applied to the face of the propeller blades. The quasi-static calculations otherwise show that the materials are similar and there is no significant difference in their failure points. The fluid dynamics calculations show that there is limited differences between the two propeller materials. A slight advantage in thrust generated is seen for the traditional material and the composite material also suffers from significant wall shear stress due to the characteristic roughness of its surface. The project concludes by determining that CFRP is a suitable material for a high-performance boat propeller but that the material could only be used if design considerations were made. The project also finds that due to the significant deformation in the composite material there may be an impact on the composite propellers ability to generate thrust. Thus, supporting the early conclusion that design considerations would be required if a composite material was to be used.